A liquid crystal display mainly comprises an array substrate, which is provided with pixel units arranged in a matrix form thereon, each pixel unit is provided with a thin film transistor and a pixel electrode therein, wherein the thin film transistor controls the application of voltage to the pixel unit.
Specifically, the thin film transistor comprises an active layer, a gate insulation layer, a gate, an interlayer insulation layer, a source and a drain which are provided sequentially. As for the thin film transistor with above structure, in a case that the thin film transistor is in an off state, there is still a current in the thin film transistor, this current is generally referred as a leakage current of the thin film transistor. Specifically, the leakage current of the thin film transistor includes a main leakage current of the thin film transistor between the source and the drain and an edge leakage current of the thin film transistor consisting of a leakage current between the gate and the source and a leakage current between the gate and the drain, wherein a proportion of the main leakage current of the thin film transistor in the leakage current of the thin film transistor is larger.
Too large leakage current of the thin film transistor may cause disadvantages such as deviation of display gray scale of the pixel electrode of the liquid crystal display, and increased energy consumption of the liquid crystal.